This phase II/III trial studies the best dose of duloxetine and how well it works in preventing pain, tingling, and numbness (peripheral neuropathy) caused by treatment with oxaliplatin in patients with stage II-III colorectal cancer. Duloxetine increases the amount of certain chemicals in the brain that help relieve depression and pain. Giving duloxetine in patients undergoing treatment with oxaliplatin for colorectal cancer may help prevent peripheral neuropathy.